USA — Arizonas forests must be thinned to address overgrowth that harms watersheds and endangers wildlife and surrounding communities, the states top forestry official told lawmwakers Thursday.

We have too many trees, State Forester Scott Hunt told the House Agriculture and Water Committee.

Hunt said thick forest canopies and underbrush intercept a lot of rain and snow that otherwise would reach watersheds, causing it to evaporate, and an overabundance of trees draws up and transpires even more water.

Thinner forests more efficiently convert snowpack into stream flow, he said, citing a study showing that water yields can be increased between 15-40 percent when ponderosa pine forests are thinned.

Healthy forests are the foundation of healthy watersheds, and healthy watersheds, conversely, are the foundations of healthy forests, he said.

Hunt showed lawmakers a picture of the same patch of forest in 1875 and 2003. The older landscape had far fewer trees, he said, because natural fires cleared smaller trees and underbrush while preserving older trees, he said.

What happens when we have a lot of trees together is that when we have fires they are high-intensity, catastrophic, they threaten our communities, he said.

Other challenges to the health of Arizonas forests include increasing temperatures and insect outbreaks, Hunt said.

The forests are in an unhealthy state, and were trying to get them back to a restorative state, he said.

Weve had 100 years of policies that have created these conditions, Bahr said in a telephone interview. What needs to happen is thinning and the reintroduction of fire to restore the natural processes.